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  <title>返回数组中指定的一列</title>
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 <body class="docs"><div id="layout">
  <div id="layout-content"><div id="function.array-column" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">array_column</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.5.0, PHP 7)</p><p class="refpurpose"><span class="refname">array_column</span> &mdash; <span class="dc-title">返回数组中指定的一列</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.array-column-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>array_column</strong></span>
    ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$input</code></span>
   , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$column_key</code></span>
   [, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$index_key</code><span class="initializer"> = null</span></span>
  ] ) : <span class="type">array</span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>array_column()</strong></span>
   返回<code class="parameter">input</code>数组中键值为<code class="parameter">column_key</code>的列，
   如果指定了可选参数<code class="parameter">index_key</code>，那么<code class="parameter">input</code>数组中的这一列的值将作为返回数组中对应值的键。
  </p>
 </div>

 <div class="refsect1 parameters" id="refsect1-function.array-column-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">input</code></dt>

     <dd>

      <p class="para">
       需要取出数组列的多维数组。
       如果提供的是包含一组对象的数组，只有 public 属性会被直接取出。
       为了也能取出 private 和 protected 属性，类必须实现
       <span class="function"><strong>__get()</strong></span> 和 <span class="function"><strong>__isset()</strong></span> 魔术方法。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">column_key</code></dt>

     <dd>

      <p class="para">
       需要返回值的列，它可以是索引数组的列索引，或者是关联数组的列的键，也可以是属性名。
       也可以是<strong><code>NULL</code></strong>，此时将返回整个数组（配合<code class="parameter">index_key</code>参数来重置数组键的时候，非常管用）
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">index_key</code></dt>

     <dd>

      <p class="para">
       作为返回数组的索引/键的列，它可以是该列的整数索引，或者字符串键值。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.array-column-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   从多维数组中返回单列数组。
  </p>
 </div>

 <div class="refsect1 changelog" id="refsect1-function.array-column-changelog">
  <h3 class="title">更新日志</h3>
  <p class="para">
   <table class="doctable informaltable">
    
     <thead>
      <tr>
       <th>版本</th>
       <th>说明</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td>7.0.0</td>
       <td>
         <code class="parameter">input</code> 参数现在可以是包含对象的数组。
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.array-column-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-6013">
    <p><strong>Example #1 从结果集中取出first names列</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;Array&nbsp;representing&nbsp;a&nbsp;possible&nbsp;record&nbsp;set&nbsp;returned&nbsp;from&nbsp;a&nbsp;database<br /></span><span style="color: #0000BB">$records&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">2135</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'John'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">3245</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Sally'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Smith'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">5342</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Jones'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">5623</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Peter'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;)<br />);<br />&nbsp;<br /></span><span style="color: #0000BB">$first_names&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'first_name'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$first_names</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; John
    [1] =&gt; Sally
    [2] =&gt; Jane
    [3] =&gt; Peter
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-6014">
    <p><strong>Example #2 
     从结果集中总取出last names列，用相应的id作为键值
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;Using&nbsp;the&nbsp;$records&nbsp;array&nbsp;from&nbsp;Example&nbsp;#1<br /></span><span style="color: #0000BB">$last_names&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'last_name'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'id'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$last_names</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [2135] =&gt; Doe
    [3245] =&gt; Smith
    [5342] =&gt; Jones
    [5623] =&gt; Doe
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-6015">
    <p><strong>Example #3 
     username 列是从对象获取 public 的 &quot;username&quot; 属性
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">User<br /></span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;</span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string&nbsp;$username</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">username&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #0000BB">$users&nbsp;</span><span style="color: #007700">=&nbsp;[<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;1'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;2'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;3'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$users</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'username'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; user 1
    [1] =&gt; user 2
    [2] =&gt; user 3
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-6016">
    <p><strong>Example #4 
     获取  username 列，从对象通过魔术方法  <span class="function"><strong>__get()</strong></span> 获取 private 的 &quot;username&quot; 属性。
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">Person<br /></span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;private&nbsp;</span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string&nbsp;$name</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">name&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__get</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">$prop</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__isset</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">)&nbsp;:&nbsp;</span><span style="color: #0000BB">bool<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;isset(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">$prop</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #0000BB">$people&nbsp;</span><span style="color: #007700">=&nbsp;[<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Fred'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'John'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$people</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'name'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; Fred
    [1] =&gt; Jane
    [2] =&gt; John
)
</pre></div>
    </div>
   </div>
   如果不提供<span class="function"><strong>__isset()</strong></span>，会返回空数组。
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.array-column-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member">
     <a href="https://github.com/ramsey/array_column/blob/master/src/array_column.php" class="link external">&raquo;&nbsp;Recommended
     userland implementation for PHP lower than 5.5</a>
    </li>
   </ul>
  </p>
 </div>

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